Image forming apparatus

Abstract

Disclosed is an image forming apparatus that comprises: an image bearing member; an image forming unit for forming a toner image on the image bearing member; an intermediate transfer member; a first transfer device for transferring the toner image on the image bearing member onto the intermediate transfer member; a second transfer device for transferring the toner image on the intermediate transfer member onto a transfer material; an intermediate transfer member cleaner for cleaning the intermediate transfer member after the transfer; a charging unit for giving the electric charge to the intermediate transfer member; and a control unit by which, when the charging unit is controlled, in non-image area on the intermediate transfer member, the intermediate transfer member is charged to the reverse polarity to the charge of toner, and the toner adhered to the second transfer device is transferred to the intermediate transfer member.

1 . An image forming apparatus comprising: 
 an image bearing member;    an image forming unit for forming a toner image on the image bearing member;    an intermediate transfer member;    a first transfer device for transferring the toner image on the image bearing member onto the intermediate transfer member;    a second transfer device for transferring the toner image on the intermediate transfer member onto a transfer material;    an intermediate transfer member cleaner for cleaning the intermediate transfer member after the transfer;    a charging unit for giving the electric charge to the intermediate transfer member; and    a control unit by which, when the charging unit is controlled, in non-image area on the intermediate transfer member, the intermediate transfer member is charged to the reverse polarity to the charge of toner, and the toner adhered to the second transfer device is transferred to the intermediate transfer member.    
   
   
       2 . The image forming apparatus of  claim 1 , wherein the second transfer device includes a transfer roller and a power source for applying the transfer voltage on the transfer roller.  
   
   
       3 . The image forming apparatus of  claim 1 , wherein the charging unit is arranged between the first transfer device and the second transfer device.  
   
   
       4 . The image forming apparatus of  claim 1 , wherein the charging unit includes a charging electrode and a scorotron charger having a grid, and the control unit controls the charging unit in such a manner that, in the image area on the intermediate transfer member, the charging unit applies the voltage of the reverse polarity to the charge of toner onto the charging electrode, the intermediate transfer member is charged by the charging unit whose grid is set to the potential of the same polarity as the charge of toner, the toner image is transferred from the intermediate transfer member onto the transfer material, and in the non-image area on the intermediate transfer member, the voltage of the reverse polarity to the charge of toner is applied onto the charging electrode, the intermediate transfer member is charged by the charging unit whose grid is set to the potential of the reverse polarity to the charge of toner, and the toner on the second transfer device is transferred to the intermediate transfer member.  
   
   
       5 . An image forming apparatus comprising: 
 an image bearing member;    an image forming unit for forming the toner image on the image bearing member;    an intermediate transfer member;    a first transfer device for transferring the toner image on the image bearing member onto the intermediate transfer member;    a second transfer device for transferring the toner image on the intermediate transfer member onto a transfer material;    an intermediate transfer member cleaner for cleaning the intermediate transfer member after the transfer;    a charging unit for discharging the intermediate transfer member; and    a control unit for controlling the second transfer device and the charging unit so that, in the non-image area on the intermediate transfer member, the intermediate transfer member is discharged by the charging unit, and the inverse transfer by which the toner is transferred from the second transfer device to the discharged intermediate transfer member, is conducted.    
   
   
       6 . The image forming apparatus of  claim 5 , wherein the second transfer device includes the transfer roller, and the power source for applying the voltage on the transfer roller, and the control unit, by controlling the power source, conducts the transfer of the toner image onto the transfer material and the inverse transfer of the toner onto the intermediate transfer member.  
   
   
       7 . The image forming apparatus of  claim 5 , wherein the charging unit is arranged between the first transfer device and the second transfer device.  
   
   
       8 . The image forming apparatus of  claim 5 , wherein the charging unit charges the intermediate transfer member in the image area of the intermediate transfer member, and the control unit changes the operation condition of the charging unit in the image area and in the non-image area.  
   
   
       9 . An image forming apparatus comprising: 
 an image bearing member;    an image forming unit for forming the toner image on the image bearing member;    an intermediate transfer member;    a first transfer unit for transferring the toner image on the image bearing member onto the intermediate transfer member;    a second transfer unit having a transfer roller which can be brought into contact with and separated from the intermediate transfer member, and for transferring the toner image on the intermediate transfer member onto a transfer material;    an intermediate transfer member cleaner for cleaning the intermediate transfer member after the transfer;    a charging unit for applying an electric charge to the intermediate transfer member; and    a control unit for timing-controlling the charging unit so that the charging unit charges the intermediate transfer member to the reverse polarity to the charge of toner, to the leading edge area, which adjoins the leading edge part of the image area, and includes an area in which the transfer roller is brought into contact with the intermediate transfer member, and to the trailing edge area, which adjoins the trailing edge part of the image area, and includes an area in which the transfer roller is brought into contact with the intermediate transfer member.    
   
   
       10 . The image forming apparatus of  claim 9 , wherein the charging unit includes a scorotron charger having a charging electrode and a grid, and the control unit applies the voltage of the reverse polarity to the charge of toner onto the charging electrode, and when the grid is set to the potential of the reverse polarity to the charge of toner, charges the intermediate transfer member in the leading edge area and the trailing edge area.  
   
   
       11 . An image forming apparatus comprising: 
 an image bearing member;    an image forming unit for forming the toner image on the image bearing member;    an intermediate transfer member;    a first transfer device for transferring the toner image on the image bearing member onto the intermediate transfer member;    a second transfer device having a transfer roller, and for transferring the toner image on the intermediate transfer member onto a transfer material;    an intermediate transfer member cleaner for cleaning the intermediate transfer member after the transfer; and    a charging unit for applying an electric charge to the intermediate transfer member, wherein, when the cleaning width of the intermediate transfer member is H 3 , the charging width of the charging unit is H 2 , and the length of the transfer roller is H 1 , then, H 1 ≦H 2 ≦H 3  is satisfied.    
   
   
       12 . The image forming apparatus of  claim 11 , wherein the charging unit charges the intermediate transfer member so that the absolute value of the potential of the toner image on the intermediate transfer member is lowered.  
   
   
       13 . The image forming apparatus of  claim 12 , wherein the intermediate transfer member cleaner has a cleaning roller.  
   
   
       14 . An image forming apparatus comprising: 
 an image bearing member;    an image forming unit for forming the toner image on the image bearing member;    an intermediate transfer member;    a first transfer device for transferring the toner image on the image bearing member onto the intermediate transfer member;    a second transfer device for transferring the toner image on the intermediate transfer member onto a transfer material;    an intermediate transfer member cleaner for cleaning the intermediate transfer member after the transfer;    a charging unit for applying an electric charge to the intermediate transfer member; and    a control unit for controlling the charging unit, in the non-image area, when the charging unit charges the intermediate transfer member to the reverse polarity to the charge of toner, so that the toner adhered to the intermediate transfer member cleaner is moved to the intermediate transfer member.    
   
   
       15 . The image forming apparatus of  claim 14 , wherein the intermediate transfer member cleaner has a cleaning roller which is electrically grounded or on which the voltage is applied.  
   
   
       16 . The image forming apparatus of  claim 14 , wherein the control unit changes the operation condition of the charging unit in the image area and in the non-image area.  
   
   
       17 . An image forming apparatus comprising: 
 an image bearing member;    an image forming unit for forming the toner image on the image bearing member;    an intermediate transfer member;    a first transfer unit for transferring the toner image on the image bearing member onto the intermediate transfer member;    a second transfer unit for transferring the toner image on the intermediate transfer member onto a transfer material;    an intermediate transfer member cleaner having a cleaning member and the power source to apply the voltage on the cleaning member, and for cleaning the intermediate transfer member after the transfer;    a charging unit for applying an electric charge to the intermediate transfer member; and    a control unit for controlling the charging unit so that the charging unit discharges the intermediate transfer member, and for controlling the power source so that the toner is transferred from the cleaning member onto the discharged intermediate transfer member.    
   
   
       18 . The image forming apparatus of  claim 17 , wherein the control unit changes the operation condition of the charging unit in the image area and in the non-image area.